Studio Technologies M212-00151 - Manual (Page 27)

Model 212 User Guide Issue 2, June 2006
Studio Technologies, Inc. Page 28
as specified in the IEC 61938 standard.
The required circuitry is very simple: two
6.81 k ohm resistors provide a path from a
48 volt source to pins 2 and 3 of the micro-
phone input connector. The resistors and
the power source work together to provide
48 ±4 volts, up to a maximum current of
10 milliamperes.
LED Colors
As previously described, two LED indica-
tors are associated with the main output
and are located directly above the main
output pushbutton switch. The red LED,
located on the left, is lit whenever the
main output channel is muted. The green
LED, located on the right, is lit whenever
the main output channel is active. The
thought behind the color choices was
that red would relate to the main output
channel being muted (“stop”) while green
would relate to the main output channel
being active (“go”). It’s possible that these
color choices may not meet the needs of
all users and applications. For example,
it’s reported that one European broad-
caster typically uses these two colors in
the opposite fashion. Their choice is to
have the red LED lit whenever the main
output channel is active, warning the tal-
ent that they are “on-air.” The green LED
is lit whenever the main output channel
is muted, indicating to the talent that it’s
“safe” to say whatever they wish, about
whomever they wish to say it about!
For consistency, the LED associated with
the talkback button was selected to be
green. This lights whenever the talkback
channel is active. It’s possible that some
applications may benefit from revising
this LED color too. While red is certainly
one possible choice, other colors are also
a possibility including amber, orange, or
blue—these days there are lots of choices
available. The only limitation is the amount
of current available to light each LED.
Using series resistors of no less than
560 ohms will ensure correct Model 212
operation.
A qualified technician can easily revise the
LED colors to meet an application’s exact
needs. The process would begin by disas-
sembling the Model 212’s enclosure and
detaching the pushbutton/LED printed
circuit board assembly. The LEDs would
then be unsoldered, removed, and rein-
stalled (or replaced) in the desired loca-
tions. To control the LED current and set
the brightness, a resistor is electrically in
series with each LED. From the factory,
an 820 ohm, ¼-watt resistor is associated
with the red LED while a 560 ohm, ¼-watt
resistor is associated with each green
LED. These resistors would also have to
be unsoldered, removed, and reinstalled.
Then the unit would be reassembled and
tested to confirm that the changes func-
tion as desired.
For additional information about chang-
ing the LED colors, please contact Studio
Technologies’ technical support.
Travel Case
For portable applications it may be desir-
able to store and transport each Model
212 in a protective case. After much travel
with prototype announcer console units,
Studio Technologies’ personnel learned
to appreciate the Pelican Model 1450
case. Purchased with the foam interior
option, it does an excellent job of holding
one Model 212, its associated 24 volt DC
power supply, and documentation. Some
applications may benefit from selecting a
larger case that would also hold a related
headset, cables, etc. A larger case could